Grade 11 Chemistry - Energy Changes & Reaction Rates

Flashcards covering key vocabulary and concepts from a Grade 11 Chemistry revision booklet on Energy Changes & Reaction Rates.

Exothermic Reaction

A reaction that releases heat to the surroundings, increasing the temperature and having a negative enthalpy change (ΔH).

Endothermic Reaction

A reaction that absorbs heat from the surroundings, decreasing the temperature and having a positive enthalpy change (ΔH).

Enthalpy (ΔH)

The total heat content of a system at constant pressure, measured in kilojoules per mole (kJ/mol). A negative ΔH indicates an exothermic reaction, while a positive ΔH indicates an endothermic reaction.

Activation Energy

The minimum energy required to start a chemical reaction.

Reaction Rate

How quickly a chemical reaction occurs, measured by the amount of reactants used or products formed over time.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed in the process by lowering the activation energy.

Exothermic Reaction Diagram

Reactants start high → energy released → products end lower. ΔH is negative.

Endothermic Reaction Diagram

Reactants start low → energy absorbed → products end higher. ΔH is positive.